Dioxaphosphorinane derivatives as flameproofing agents

ABSTRACT

Flameproofed polymeric organic materials, e.g. regenerated cellulose, which include bis-(2-oxo-1,3, 2-dioxaphosphorinanyl) oxides, bis-(2-thiono-1,3,2 -dioxaphosphorinanyl) oxides and 2-oxo-1,3,2-dioxaphosphorinanyl-2&#39;-thiono-1&#39;,3&#39;,2&#39;-dioxaphosphorinanyl oxides, having at least one substituent on the dioxaphosphorinane rings, as flameproofing agents, and their production. Some of the flameproofing agents are new compounds and are included in the invention.

The present invention relates to flameproofed polymeric organicmaterials which include dioxaphosphorinane derivatives as flameproofingagents. More particularly, the flameproofing dioxaphosphorinanederivatives are chosen from bis-(2-oxo-1,3,2-dioxaphosphorinanyl)oxides,bis-(2-thiono-1,3,2-dioxaphosphorinanyl)oxides and2-oxo-1,3,2-dioxaphosphorinanyl-2'-thiono-1',3',2'-dioxaphosphorinanyloxides having at least one substituent on the dioxaphosphorinane rings.

Accordingly the present invention provides a flameproofed polymericorganic material including as a flameproofing agent a compound offormula I, ##STR1## in which each X, independently, is oxygen orsulphur,

each R₁, independently, is hydrogen, C₁ -C₄ alkyl, chloromethyl,bromomethyl or phenyl,

each R₂, independently, is hydrogen, C₁ -C₄ alkyl, chloromethyl orbromomethyl,

or R₁ and R₂, together with the carbon atom to which each is attached,on each dioxaphosphorinane ring independently, complete a cyclohexane,cyclohexene or 3,4-dibromocyclohexane ring,

each of R₃ and R₅, independently, is hydrogen or C₁ -C₄ alkyl, and

each R₄, independently, is hydrogen or methyl,

with the provisos (i) that at least one of R₁, R₂, R₃, R₄ and R₅ fromeach dioxaphosphorinane ring is other than hydrogen, (ii) that when, ona dioxaphosphorinane ring, each of R₁ and R₂, independently, ischloromethyl or bromomethyl or R₁ and R₂ together with the carbon atomto which each is attached complete a ring, then each of R₃, R₄ and R₅ onthat same dioxaphosphorinane ring is hydrogen, and (iii) when, on adioxaphosphorinane ring, X is oxygen, then each of R₁ and R₂,independently, is chloromethyl or bromomethyl, or R₁ and R₂ togetherwith the carbon atom to which each is attached, complete a ring.

In the above definition of formula I, it is to be understood that anyalkyl radical represented by each R₁, R₂, R₃ and R₅, may be straight orbranched chain when containing 3 or 4 carbon atoms, and thus may be n-or isopropyl or n-, iso- or tert.-butyl.

When either R₁ or either R₂ is alkyl, this preferably contains 1 to 3,more preferably 1 or 2 carbon atoms, and most preferably is methyl.

When either R₁ or either R₂ is chloro- or bromomethyl, this ispreferably bromomethyl.

When either R₁ and R₂ bound to a common carbon atom complete a ring withthat common carbon atom, this is preferably a cyclohexene or the3,4-dibromocyclohexane ring.

Preferably both X's, simultaneously, are oxygen or sulphur, and morepreferably, both X's are sulphur.

Each R₁ and R₂, independently, is preferably chloromethyl, bromomethyl,or, in the case when X on the same dioxaphosphorinane ring is sulphur,alkyl, or either R₁ and R₂, independently, together with the carbon atomto which each is attached, preferably complete a cyclohexane,cyclohexene or 3,4-dibromocyclohexane ring. More preferably, both R₁ 'sand both R₂ 's simultaneously are chloromethyl, bromomethyl or, in thecase when both X's simultaneously on the dioxaphosphorinane rings aresulphur, alkyl, or R₁ and R₂, together with the carbon atom to whicheach is attached, on both dioxaphosphorinane rings simultaneously,complete a cyclohexane, cyclohexene or 3,4-dibromocyclohexane ring. Mostpreferably, both R₁ 's and both R₂ 's simultaneously are chloromethyl,bromomethyl or alkyl.

Preferably each of the R₃ 's, R₄ 's and R₅ 's, independently, ishydrogen.

The flameproofed polymeric organic material of the present inventionpreferably includes as a flameproofing agent a compound of formula Ia,##STR2## in which both X''s, simultaneously, are oxygen or sulphur,

and each R₁ ' and each R₂ ', independently, is chloromethyl, bromomethylor additionally, in the case when the X''s are sulphur, C₁ -C₄ alkyl,

or R₁ ' and R₂ ', together with the carbon atom to which each isattached, on each dioxaphosphorinane ring independently, complete acyclohexane, cyclohexene or 3,4-dibromocyclohexane ring.

More preferably, the flameproofing agent included in the flameproofedpolymeric organic material is a compound of formula Ib, ##STR3## inwhich both X''s are oxygen or sulphur, and both R₁ "'s and both R₂ "'s,simultaneously, are bromomethyl, or, in the case when the X''s aresulphur, each R₁ " and each R₂ ", independently, is bromomethyl,chloromethyl, methyl, ethyl or propyl,

or R₁ " and R₂ ", together with the carbon atom to which each isattached, on both dioxaphosphorinane rings simultaneously, complete acyclohexene or 3,4-dibromocyclohexane ring.

Even more preferably, the flameproofing agent included in theflameproofed polymeric organic material is a compound of formula Ic,##STR4## in which both R₁ "''s and both R₂ "''s simultaneously, aremethyl, ethyl, chloromethyl or bromomethyl.

Most preferably, the flameproofed polymeric organic material of thepresent invention includes as a flameproofing agent a compound offormula Id, ##STR5## in which both R₁ ""'s and both R₂ ""'s,simultaneously, are methyl or bromomethyl.

The compounds of formula I', ##STR6## in which each of the Xa's, R_(1a)'s, R_(2a) 's, R_(3a) 's, R_(4a) 's, and R_(5a) 's, independently, hasthe meaning of each of the X's, R₁ 's, R₂ 's, R₃ 's, R₄ 's and R₅ 's,respectively, given in the definition of formula I, above, the provisos(i), (ii) and (iii) given in that definition apply, and in addition withthe proviso (iv) that when, on a dioxaphosphorinane ring, Xa is sulphur,R_(1a) is methyl and R_(2a) is hydrogen or methyl, then at least one ofR_(3a), R_(4a) and R_(5a) on that same dioxaphosphorinane ring isdifferent from hydrogen, are new, and are also provided by the presentinvention.

The present invention further provides a process for the production of acompound of formula I', as defined above, which comprises hydrolysingone or two compounds of formula II, ##STR7## in which Xa, R_(1a),R_(2a), R_(3a), R_(4a) and R_(5a) are as defined above,

with water in the presence of a base.

A suitable base of use in the process of the present invention ispyridine. It is to be understood that when one compound of formula II isused in the above process, the product is structurally symmetrical.

Intermediates of formula II, as defined above, may be produced inconventional manner from known starting materials or from startingmaterials produced by analogous processes to those for producing theknown starting materials.

The particular compounds, ##STR8## are new and also form part of thepresent invention. They may be produced in conventional manner byreacting phosphoryl or thiophosphoryl chloride, respectively, with1,1-dihydroxymethyl-3,4-dibromocyclohexane, or by bromine addition onthe corresponding 3,4-cyclohexene derivatives of the products,themselves known from German Pat. No. 1,051,279.

The compounds of formula I, other than those of formula I', may beproduced in analogous manner to those of formula I' as described above.

In the flameproofed polymeric organic materials of the presentinvention, preferred organic materials rendered flameproofed by theinclusion of a compound of formula I, as defined above, are regeneratedcellulose, polyolefins, e.g. polyethylene and polypropylene, polyesters,polyacrylic esters, e.g. polymethyl methacrylates, polyphenylene oxides,polyurethanes, polystyrene, polyamides, e.g. nylon, polypropylene oxide,polyacrylonitrile, copolymers of the aforementioned polymers,acrylonitrile-butadiene-styrene (ABS) terpolymers, and natural fibrousmaterials, e.g. cotton. More preferably, the organic materials areregenerated cellulose, polyethylene, polypropylene, polyesters,polyamides, copolymers of styrene and acrylonitrile and of styrene andbutadiene, ABS-terpolymers and terpolymers of acrylic ester, styrene andacrylonitrile, and cotton of which regenerated cellulose is the mostpreferred.

The present invention further provides a method of producing aflameproofed polymeric organic material comprising treating thepolymeric organic material directly or indirectly with aflameproofing-effective amount of a compound of formula I, ashereinbefore defined. Suitable polymeric organic materials which areflameproofed according to the method of the present invention includethose mentioned above.

In this specification, by the term "treating" is meant eitherincorporating into the body of the polymeric organic material or surfacecoating such material, depending upon the substrate to be flameproofed.

The method may be carried out in a manner known per se, of which thefollowing embodiments, which relate to the production of flameproofedpolymeric organic materials other than regenerated cellulose and naturalfibrous materials, are examples:

According to a first embodiment of the method of the present invention,the compound of formula I is mixed with a kneadable polymeric organicmaterial, e.g. in particulate form, in a kneader or other suitablemixing device, to obtain the desired direct incorporation of thecompound in the organic material. The latter may then be formed into thedesired final shape, e.g. by extrusion into the form of, inter alia,films or fibres, or by injection moulding or spinning.

In a second embodiment, the compound of formula I is mixed with theappropriate monomer(s) and/or prepolymer before polymerisation orcopolymerisation is effected, whereafter the polymerised product, withthe compound distributed therethrough, may be extruded, injectionmoulded or otherwise formed into final shape. This embodiment isparticularly suitable for producing flameproofed polyurethanes andpolyolefins, and illustrates the indirect incorporation of the compoundin the organic material.

In a third embodiment, the compound of formula I is mixed with thepolymeric organic material in molten form, after which the flameproofedmaterial may be converted into the desired final shape e.g. by extrusioninto, inter alia, films, injection moulding and spinning to producefibres. This embodiment is particularly suitable for producingflameproofed polypropylene and provides a further illustration of directincorporation.

The amount of flameproofing compound of formula I suitably incorporatedinto the polymeric organic material, other than regenerated celluloseand natural fibrous materials for imparting satisfactory flameproofingproperties thereto will naturally depend on several factors, includingthe particular compound of formula I employed, the nature of the organicmaterial to be flameproofed and the mode of incorporation. However,satisfactory results are generally obtained when the amount of compoundemployed is in the range 1 to 40%, preferably 2 to 10%, and morepreferably 2 to 6%, of the weight of the polymeric organic material tobe flameproofed.

The method of the present invention is particularly suitable for theproduction of flameproofed regenerated cellulose. In this case, themethod comprises regenerating cellulose from its solution e.g. viscose,containing a compound of formula I, as defined above. Thus theregenerated cellulose produced has the compound incorporated therein andis flameproofed by virtue of its presence.

The term "regenerated cellulose" is well understood in the art to whichit pertains. Amongst the procedures for producing regenerated celluloseare those involving the formation at one stage of alkali cellulosexanthate or a tetramine cupric hydroxide complex of cellulose, and suchprocedures are so adapted according to this embodiment of the method toinclude the regeneration of cellulose from its solution containing thecompound of formula I as a flameproofing agent.

Prior to the regeneration, cellulose is brought into solution, e.g. bysuch known processes as converting it into a soluble derivative by thexanthate method or through formation of the tetramine cupric hydroxidecomplex thereof. The compound of formula I is then added to thecellulose solution, for example by itself or as a fine dispersion inwater. When added alone, the compound may be introduced into thecellulose solution either continuously or discontinuously, i.e. inbatches, and thereafter vigorous stirring of the cellulose solutioncontaining the compound may be applied to distribute it uniformly in thesolution. The same technique may also be adopted for the addition of anaqueous dispersion of the compound. Preferably the weight of compound offormula I present in the cellulose solution from which flameproofedregenerated cellulose is to be produced is in the range 5 to 35% of theweight of the cellulose starting material, e.g. α-cellulose, or morepreferably 10 to 25% of its weight. In all cases it can be advantageousto add conventional dispersion stabilisers and/or dispersion agents tothe cellulose medium to promote uniformity of distribution of thecompound in the cellulose solution.

Other flameproofing compounds, e.g. reaction products of a phosphorusnitrile chloride with glycols e.g. neopentylglycol or other glycols, asdescribed in German Offenlegungsschrift No. 2,316,959, orcyclodiphosphazanes or thionocyclodiphosphazanes, as described in GermanOffenlegungsschrift No. 2,451,802, may be added to the cellulosesolution as well as a compound of formula I. The amount of suchadditional flameproofing agents when employed may be up to 90% by weightof the total flameproofing agent present in the cellulose solution. Inthe case of reaction products of a phosphorus nitrile chloride and aglycol, cyclodiphosphazane and thionocyclodiphosphazane, such auxiliaryflameproofing agent preferably constitutes 10 to 70%, or more preferably15 to 60%, of the total weight of flameproofing agent in the solution.

The regenerated cellulose is produced in shaped form from the solutionin conventional manner by forcing the solution into a precipitation baththrough fine nozzles or slots, thereby producing filaments or sheets,respectively. Apart from flame resistance, the so-produced flameproofedregenerated cellulose possesses its normal technically importantproperties which are only slightly affected by the presence of theincorporated flameproofing agent.

Natural fibrous materials are treated, according to the method of thepresent invention, by coating the compound of formula I, suitablypresent in a coating liquor, onto the substrate. Thus the material istreated directly with the compound of formula I. Where blend fabrics ofsynthetic and/or semi-synthetic and natural fibrous organic materialse.g. polyester-cotton blend fabrics, are to be flameproofed, thesynthetic or semisynthetic organic material may be independently treatedaccording to the method of the invention, e.g. as described in the aboveembodiments, and then blended with the natural fibrous organic material,the blend fabric then being optionally further treated with a compoundof formula I by coating if a higher degree of flameproofing is necessaryor desired. Alternatively, the untreated blend fabric may be treatedwith the compound by coating.

The present invention is illustrated by the following Examples, in whichthe parts and percentages are by weight.

EXAMPLE 1

To a solution of 338.8 parts of thiophosphoryl chloride in 3000 parts ofbenzene are added 314.4 parts of pyridine at 20° C. followed by 523.9parts of 2,2-bis(bromomethyl)-1,3-propanediol at 20° to 35° C. over aperiod of 30 minutes. The mixture is then stirred at 50° C. for 24hours, cooled to 20° C., and filtered. On evaporation of the filtrate invacuo, 743 parts of impure2-chloro-2-thio-5,5-bis(bromomethyl)-1,3,2-dioxaphosphorinane, offormula, ##STR9## are obtained. Recrystallisation from carbontetrachloride results in a purer product, m.p. 106°-108° C.

To a solution of 71.7 parts of the above intermediate in 136 parts oftetrahydrofuran are added to 16.3 parts of pyridine and 1.8 parts ofwater. The mixture is stirred at a reflux temperature for 4 hours. Afterthe completion of the reaction the mixture is cooled to 20° C. and 300parts of ethyl acetate are added. The mixture is washed with water andafter concentration of the organic phase 38 parts of a compound of theformula, ##STR10## having a melting point of 190°-192° crystallise out.Crystallisation from benzene results in a purer product m.p. 198°-199°C.

This is a new compound and forms part of the present invention.

EXAMPLES 2 to 18

The following compounds are produced in an analogous manner to thatdescribed in Example 1.

    __________________________________________________________________________    Example                                                                            Structure             Melting Point (°C.)                         __________________________________________________________________________          ##STR11##            174°-175°                            3                                                                                   ##STR12##            228°-229°                            4                                                                                   ##STR13##            199°-200°                            5                                                                                   ##STR14##            134°-136°                            6                                                                                   ##STR15##            139°-140°                            7                                                                                   ##STR16##            139°-141°                            8                                                                                   ##STR17##                                                               (liquid)                                                                      9                                                                                   ##STR18##            240°-242°                            10                                                                                  ##STR19##            187°-188°                            11                                                                                  ##STR20##            228° with  decomposition                    12                                                                                  ##STR21##            106°-108°                            13                                                                                  ##STR22##            157°-158°                            14                                                                                  ##STR23##                                                               (liquid)                                                                      15                                                                                  ##STR24##            159°-160°                            16                                                                                  ##STR25##            161°-163°                            17                                                                                  ##STR26##            239°-241°                            18                                                                                  ##STR27##            140° with decomposition                     __________________________________________________________________________

All the compounds except that of Example 3 are new, and so form part ofthe present invention.

In the case of the production of the compounds of Examples 2, 17 and 18,phosphoryl chloride is used instead of thiophosphoryl chloride, as inthe remaining Examples, as a starting material. In many cases it isunnecessary to use pyridine and benzene in the production of theintermediate substituted 2-chloro-2-oxy orthio-1,3,2-dioxaphosphorinane. For the production of the final productfrom the aforementioned intermediate an excess of pyridine instead of asolvent such as tetrahydrofuran, as in Example 1, may be used in manycases.

The mode of isolation of a reaction product from the reaction mixture isdependent on the solubility and the state of aggregation of theparticular compound. If precipitated during the reaction, the compoundmay be collected by filtration and washed with water. However, if itremains dissolved in the reaction liquor, its precipitation therefrommay be induced by addition of a diluent such as water. In the case of aproduct normally in a liquid state, such as the compounds of Examples 8and 14, it is generally appropriate to filter the reaction mixture,concentrate the filtrate in vacuo, dissolve the residue in diethylether, wash the etheral solution with water, remove the ether solvent byevaporation in vacuo and distil the oil residue, removing volatileimpurities at about 50° C. at less than 0.1 mm. of mercury pressure.

As well as by hydrolysing the appropriate 5,5-substituted-2-chloro-2-oxyor thio-1,3,2-dioxaphosphorinane, the compounds of Examples 11 and 18may also be obtained by brominating the compounds of Examples 10 and 17,respectively.

APPLICATION EXAMPLE 1

A 22% aqueous dispersion of the compound of Example 3 is prepared asfollows: 50 parts of the compound of Example 3 are ground to a powderduring 3 hours with 12.5 parts of a dispersing agent based on sodiumnaphthalenesulphonate and 137.5 parts of water by revolution at the rateof 1500 revolutions per minute in the presence of 200 parts of quartzitebeads, cooling with ice being maintained throughout the grinding. Thequartzite beads are then removed by filtration and 180 parts of adispersion containing 22% of the compound are obtained.

16.4 Parts of the 22% aqueous dispersion are introduced with stirringinto 200 parts of a cellulose xanthate solution prepared from 18 partsof α-cellulose. The solution is forced through nozzles by a conventionalspinning process into a precipitation bath containing 125 g of sulphuricacid, 240 g of anhydrous sodium sulphate and 12 g of anhydrous zincsulphate per liter. The resulting fibres are washed thoroughly andformed into knit fabrics which are subsequently tested forflame-resistance by the method of Fenimore and Martin, described inModern Plastics, November 1966, involving the determination of theoxygen limit value (LOI). Comparison of the results with those given byuntreated regenerated cellulose indicates the flameproofing propertyimparted by the incorporated compound of Example 3.

Similarly the compounds of Examples 1, 2, 4 to 7, 9 to 13 and 15 to 18may be used for flameproofing regenerated cellulose.

APPLICATION EXAMPLE 2

3.6 Parts of the compound of Example 8 are introduced with stirring into200 parts of a cellulose xanthate solution prepared from 18 parts ofα-cellulose. The ensuing production and testing of the flameproofedcellulose is effected as described in Application Example 1.

APPLICATION EXAMPLE 3

8.2 Parts of a 22% aqueous dispersion of the compound of Example 3(produced as described in Application Example 1) and 9 parts of a 22%aqueous dispersion of 2,4-dianilino-2,4-dioxa-1,3-cyclodiphosphazane aresuccessively stirred into 200 parts of a cellulose xanthate solutionprepared from 18 parts of α-cellulose. The ensuing production andtesting of the flameproofed cellulose is effected as described inApplication Example 1.

APPLICATION EXAMPLE 4

3 Parts of the compound of Example 2 are well mixed with 100 parts ofpolypropylene powder (Propathene HM 20, obtainable from ImperialChemical Industries) in a shaking machine and the mixture is then formedinto a sheet on a "roller seat" for 5 minutes at 165° to 175° C. Aftercomminution the sheet is compressed at 220° C. at pressures of 1.5 atm.for 1.5 minutes and 30 atm. for 1.5 minutes. The sheets obtained aretested by the DIN 53438 and LOI methods.

What is claimed is:
 1. A flameproofed polymeric organic materialcontaining, as a flameproofing agent, a flameproofing effective amountof a compound of the formula, ##STR28## in which each R₁, independently,is hydrogen, C₁ -C₄ alkyl, chloromethyl, bromomethyl or phenyl,each R₂,independently, is hydrogen, C₁ -C₄ alkyl, chloromethyl or bromomethyl,or R₁ and R₂, together with the carbon atom to which each is attached,on each dioxaphosphorinane ring independently, complete a cyclohexane,cyclohexene or 3,4-dibromocyclohexane ring, each of R₃ and R₅,independently, is hydrogen or C₁ -C₄ alkyl, and each R₄, independently,is hydrogen or methyl,with the provisos (i) that at least one of R₁, R₂,R₃, R₄ and R₅ from each dioxaphosphorinane ring is other than hydrogen,and (ii) that when, on a dioxaphosphorinane ring, each of R₁ and R₂,independently, is chloromethyl or bromomethyl, or R₁ and R₂ togetherwith the carbon atom to which each is attached complete a ring, theneach of R₃, R₄ and R₅ on that same dioxaphosphorinane ring is hydrogen.2. A flameproofed polymeric organic material according to claim 1containing, as a flameproofing agent, a compound of the formula,##STR29## in which each R₁ ' and each R₂ ', independently, is C₁ -C₄alkyl, chloromethyl or bromomethyl,or R₁ ' and R₂ ', together with thecarbon atom to which each is attached, on each dioxaphosphorinane ringindependently, complete a cyclohexane, cyclohexene or3,4-dibromocyclohexane ring.
 3. A flameproofed polymeric organicmaterial according to claim 2 containing, as a flameproofing agent, acompound of the formula, ##STR30## in which each R₁ " and each R₂ ",independently, is methyl, ethyl, propyl, chloromethyl or bromomethyl,orR₁ " and R₂ ", together with the carbon atom to which each is attached,on each dioxaphosphorinane ring, complete a cyclohexene or3,4-dibromocyclohexane ring,with the proviso that when R₁ " and R₂ " andthe attached carbon atom, on both dioxaphosphorinane rings, complete acyclohexene or 3,4-dibromocyclohexane ring, both rings are identical. 4.A flameproofed polymeric organic material according to claim 1, in whichthe polymeric organic material is selected from regenerated cellulose,polyolefins, polyesters, polyacrylic esters, polyphenylene oxides,polyurethanes, polystyrene, polyamides, polypropylene oxide,polyacrylonitrile, copolymers of the aforementioned polymers,acrylonitrile-butadienestyrene terpolymers, and natural fibrousmaterials.
 5. A flameproofed polymeric organic material according toclaim 4, in which the polymeric organic material is regeneratedcellulose.
 6. A flameproofed polymeric organic material according toclaim 3 containing, as a flameproofing agent, a compound of the formula,##STR31## in which each R₁ '" and each R₂ '" is bromomethyl,chloromethyl, methyl or ethyl, the R₁ '"'s and R₂ '"'s being identical.7. A flameproofed polymeric organic material according to claim 6containing, as a flameproofing agent, a compound of the formula,##STR32## in which each R₁ "" and each R₂ "" is bromomethyl or methyl,the R₁ ""'s and R₂ ""'s being identical.
 8. A flameproofed polymericorganic material according to claim 7 containing, as a flameproofingagent, a compound of the formula, ##STR33##
 9. A method of producing aflameproofed polymeric organic material comprising treating thepolymeric organic material with a flameproofing effective amount of acompound of the formula, ##STR34## in which each R₁, independently, ishydrogen, C₁ -C₄ alkyl, chloromethyl, bromomethyl or phenyl,each R₂,independently, is hydrogen, C₁ -C₄ alkyl, chloromethyl or bromomethyl,or R₁ and R₂, together with the carbon atom to which each is attached,on each dioxaphosphorinane ring independently, complete a cyclohexane,cyclohexene or 3,4-dibromocyclohexane ring, each of R₃ and R₅,independently, is hydrogen or C₁ -C₄ alkyl, and each R₄, independently,is hydrogen or methyl,with the provisos (i) that at least one of R₁, R₂,R₃, R₄ and R₅ from each dioxaphosphorinane ring is other than hydrogen,and (ii) that when, on a dioxaphosphorinane ring, each of R₁ and R₂,independently, is chloromethyl or bromomethyl, or R₁ and R₂ togetherwith the carbon atom to which each is attached complete a ring, theneach of R₃, R₄ and R₅ on that same dioxaphosphorinane ring is hydrogen.10. A method according to claim 9, in which the polymeric organicmaterial is selected from regenerated cellulose, polyolefins,polyesters, polyacrylic esters, polyphenylene oxides, polyurethanes,polystyrene, polyamides, polypropylene oxide, polyacrylonitrile,copolymers of the aforementioned polymers,acrylonitrile-butadienestyrene terpolymers, and natural fibrousmaterials.
 11. A method according to claim 10, in which the polymericorganic material is regenerated cellulose.